Renew fuel rails essential? Opinions....
 

Hi, i wast to remove the inlet manifold on my d5 and i seems volvo recccoment renewing the fuel rails as well, reason being that if you re use the old ones they wont hold the correct pressure.

Can i have your opinions, would you change the fuel rails as well as it does double the cost of the parts from £200 to £400 approx.

Is this a moneymaking main dealer trying it on or valid? Appreciate your opinions....

In the majority of cases you can reuse the fuel delivery pipes even though it's recommended not to. You just need to be careful not to overtighten them during reinstallation. Also keep an eye on them for a while afterwards for signs of leaks. The engine will normally act up if there's an issue, but it's best to keep an eye out just incase.

Thanks, thats good advice, also when you refit them does the fuel system self prime or is there a bleed procedure on these engines?

System will self prime, you maybe want to cycle the ignition a couple of time but I have found they start straight away. Only when the filter housing is empty do they need a bit more persuasion in my experience. I found the torq settings for the fuel pipes for reassembly as to ensure not over tightening and distorting the fitting.

when you tighten the fuel pipe nuts the dome reforms to the shape of the seat in the injector making a perfect fit , Whilst doing this the metal work hardens so will not do the same a second time , It may or may not seal , but the reason you fit new pipes is safety . If a pipe should leak a small amount and you get a jet of fuel coming out , at 20,000 psi it will slice through any part of your body in range rather like a laser cutter .. up to you !

In everyday life, garages and independant mechanics aren't going to buy new fuel delivery pipes each time they change a diesel injector. In an ideal world they should be changed, but it has been proven time and time again across the world that fuel delivery pipes can be reused without issue. There are potential safety risks, but you can rest assured that if there's a leak from one of the unions, you won't feel inclined to put any of your body parts near it. If the pipes go back in the same place and are correctly torqued, you are very unlikely to have any issues.

I personally would re-use them without a second thought (and have done on many occasions). If they were to leak, although the system pressure can be considerable, the diesel would have to travel from the joint and then through the threads or top of the nuts by that point it usually trickles out. With a major unrestricted leak e.g. broken pipe the pressure in the system would collapse.

But as said there is some risk so take some care when inspecting the system afterwards with the engine running. Another common myth is that the system needs to be de-pressurised etc.

My other point would be that people would be more likely to follow Volvo’s safety guidance if the cost of the replacement pipe was reasonable..... I’ve never bought the pipes but the OP implies they are circa £200 which is not reasonable.

Thanks for he advice, do you happen to know what the torq seting is for these?:thumbs_up: